There's a certain habit that some people carry. Sometimes they know, other times, they are totally oblivious. For those that are around these people long enough, this bad habit becomes apparent. And that is being two faced. Acting or saying certain things around certain people and then doing the complete opposite when they are gone.
We all know these kinds of people. Here’s how it usually goes: Your friend complains about a certain person being annoying, or obnoxious or unreliable. The first red flag goes off and you start to wonder what this person says about you when you’re not around. But then you convince yourself that they are your friend and wouldn’t do that to you. Yet when the weekend comes and you’re looking for someone to go out with, that very friend is already out with that very same person they always complain about.
It is disrespectful, ugly and downright a waste of time being two faced. Why even bother? There was a time when you put up with these people. However, once you pass the phase of life where you think you need so many friends to be considered "cool." As you mature you start to realize it’s much more stress free and overall better to just cut everyone out that has no positive influence on you. There is no need for negativity or trying to justify to yourself that you just talked badly about somebody and now you're acting completely different to their face. It is just not right.
Not every time someone talks about someone negatively means they are two faced. I am sure we have all talked badly about someone out of frustration. However, it is when it becomes habitual and malicious that it is considered two faced. It is a little different though, if you're a pretty blunt person. If you can say what you're saying about somebody to their face, then I'm not knocking that. It's better to be known as the "blunt, bitchy, rude" friend, then to be known as a two face.